CO is not the only one with "state of the art" headphones. DL passes out the same ones except they include the "2 mono jack" adapter with theirs. I guess some of their aircraft use the have one jack systems. they suck just as bad as CO's.

what really gets me, is that they still use those air tube headphones that i used to get on Eastern airlines in the 80's. i got them on a brand new 767 not to long ago. i would bet that those are more expensive then the newer ones.